Comma 2 is unnecessary because it splits the subject clause into two parts. The specification "in Sweden and in Finland" distinguishes the research from other recent ones (for example, compare it with "the girl with the blue skirt") and as such it qualifies as necessary.
Comma 3 is definitely wrong because it splits subject and verb.
Regarding Comma 4, I would insert it, as it gives some breath to an otherwise long sentence. However, I think this is matter of personal preference rather than grammatical correctness.
I think that your student interpreted "in Sweden and in Finland" as a parenthetical element. From the link:
A parenthetical element is a word or group of words that interrupts the flow of a sentence and adds additional (but nonessential) information to that sentence.
Normally, parenthetical elements are isolated from the rest of the sentence with commas, as your student did with "in Sweden and in Finland".
Jane, the girl with the blue skirt, likes to drink green tea.
If we replace "in Sweden and Finland" with its parenthetical equivalent ("recent studies, which were conducted in Sweden and in Finland, have found out...") then comma 2 and 3 become not only correct, but also necessary; however, were we to excise the parenthetical element, the sentence would become "recent studies have found out...".